In a medium bowl, whisk together the remaining sugar, cocoa and hot water until the sugar is dissolved.

Pour the mixture over the batter in the slow cooker.

Cover and cook on high for 1 1/4 to 2 1/4 hours, depending on size of the crock pot.

Even when done, the cake will be very moist and floating on a layer of molten chocolate, but you will know it is ready when nearly all of the cake is set and the edges begin to pull away from the sides of the pot.

(As you check, try not to let the condensed steam from the lid, drip on the cake.) When it is done, turn off the power and remove the lid.

Let it cool for 25 minutes, then serve it in bowls topped with whipped cream or ice cream.